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Show 224 MR. A. H. EVERETT ON THE ZOO-GEOGRAPHICAL [Apr. 16, Borneo, are all identical with or allied to species inhabiting the latter island or other parts of Indo-Malaya proper. Not one of the few mammals which are peculiar to the Philippines is known to occur in the Palawan group. On the other hand the genera Hystrix, Manis, and Mydaus, which are such as require a continuous land-connexion to enable them to migrate from one area into another, and which are all very abundantly represented in Northern Borneo, do occur in Palawan, while none of them have been recorded as existing in the Philippines. So that a study of the relationships of the mammals of the Palawan group seems to show that this portion of the fauna was derived from Borneo and western Indo-Malaya and not from the Philippines ; and not only so, but that continuous connexion by land with Borneo must have existed so as to enable some of the genera which we find in Palawan to have reached that island. It may be argued that had such continuity of land-surface existed within the lifetime of the present fauna, the mammals of Palawan could not fail to be far more numerous than is known to be the case. But the actual junction may have been of too brief duration to allow of the migration of a large number of species; or, as is far more probable, the mammals were at one time sufficiently numerous, and they have since been almost extinguished by a general submergence of the Palawan group. There is reason to believe that the Island of Borneo has undergone in comparatively recent times a submergence to a depth of probably not less than 1000 feet, from which it is now recovering; and since Palawan appears to be partaking in the present elevatory movement, it is reasonable to conjecture that it partook also in a less or greater degree of the preceding subsidence, in which case the group must have been reduced to a chain of steep islets affording no scope for the continued existence of a varied mammalian fauna. Passing now to the birds, we find that the total number of species authentically recorded from the Palawan group amounts to 161l, which may be tabulated as follows. TABLE I.-Showing the Palawan Species which are common to Borneo or other parts of western Indo-Malaya and to the Philippines, together with the Species which are of wide general distribution or are migrants from Continental Asia. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. Phylloscopus borealis Acrocephalus orientalis. Monticola solitaria. Cisticola cisticola. Motacilla flava. Anthus maculatus. gustavi. Pericrocotus cinereus. Lalage terat. Hemichelidon sibirica. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. Musicapa griseisticta. Hypothymis occipitalis. Cidicicapa ceylonensis. Hirundo gutturalis. javanica. Sturnia violacea. Artamus leucorhynchus. Chjetura gigantea. Collocalia fuciphaga. Eurystomus orientalis. 1 I exclude Parus elegans, because the accuracy of the Palawan locality is very doubtful, and Turnix raynaldi, which Mr. Ogilvie-Grant assures m e is identical with T. nigrescens. |
